Why would the filter added to the final stage cavity be burned?

btty038

Why would the filter added to the final stage cavity be burned? [Copy link]

 

This is a high-power PW device in the L band

As shown in the picture

The design requirements of the filter are also high power

The picture below

Screw

There are traces of burns in the picture

大象慧云

maychang

“Why would the filter burn out when added to the final cavity?”

Simple: the filter can't handle that much power.

maychang

The filter always has some losses, which are converted into heat. When the heat dissipation capacity is not enough to dissipate so much heat, the filter will be damaged.

Just as a transformer will heat up and be damaged if it is overloaded (whether it is an industrial frequency transformer or a transformer in a switching power supply).

btty038

maychang posted on 2019-12-12 15:37 "Why would the filter added to the final cavity be burned?" It's simple: this filter can't withstand such a high power...

Custom-made, no problem with power handling

btty038

maychang posted on 2019-12-12 15:39 The filter always has a certain loss, which is converted into heat. When the heat dissipation capacity is not enough to dissipate so much heat, the filter will be damaged. As...

I suspect this is caused by a sudden change in the amplifier, either because the power is too high or it is resonant.

maychang

btty038 posted on 2019-12-13 14:52 I personally suspect that this is caused by the sudden change of the power amplifier, the power is too large or it is resonant

"I myself suspect that it was caused by a sudden change in the power amplifier."

It is possible. But if the amplifier is not working properly, it is also likely to be damaged.

maychang

btty038 posted on 2019-12-13 14:50 It is custom-made and can withstand power without any problems

"It is custom-made, so it can handle power without any problems."

It’s hard to say whether there will be any problems with custom-made ones.

btty038

maychang posted on 2019-12-13 15:14 "Custom-made ones will have no problem with the power they can withstand." It's hard to say if custom-made ones will have no problem.

I just don't quite understand the purpose of adding harmonics at the end. In the case of high power, is this method a bit undesirable?

maychang

btty038 posted on 2019-12-13 15:24 I just don't understand the purpose of adding it at the end. Harmonics are not a good method in the case of high power...

Your filter is probably added between the power amplifier and the antenna. I don't understand what "just added at the end" means. It seems that there is no such application method as "just adding at the end" for filters.

maychang

btty038 posted on 2019-12-13 15:24 I just don't understand the purpose of adding it at the end. Harmonics are not a good method in the case of high power...

In addition, the picture in the first post says that there are "traces of burning", but the traces of burning do not seem to be very obvious and it does not look like it has been burned.

btty038

maychang posted on 2019-12-13 16:04 In addition, the first post picture says that there are "traces of burning", but the traces of burning do not seem to be very obvious, and it does not look like it was burned...

But there will be power loss when connected, and the branch node will be damaged.

btty038

maychang posted on 2019-12-13 16:04 In addition, the first post picture says that there are "traces of burning", but the traces of burning do not seem to be very obvious, and it does not look like it was burned...

Generally, communication plus duplexer is power-bearing type, but this one is to filter out harmonics

btty038

If this function can be processed between stages, will it have a better effect than at the final stage?

btty038

maychang posted on 2019-12-13 16:04 In addition, the first post picture says that there are "traces of burning", but the traces of burning do not seem to be very obvious, and it does not look like it was burned...

I don't really understand this cavity filter. Why is it always at that fulcrum? Why do we need to make an inflection point here?

maychang

btty038 posted on 2019-12-13 16:14 Is it possible to process this function between levels? Will it have a better effect than at the end level?

If the filter is placed between stages, it will not be damaged due to the low power. However, since most power amplifiers work in Class C or Class B, it will definitely cause quite strong harmonics. If the power amplifier output is not filtered, the transmitted signal will also have strong harmonics.

maychang

btty038 posted on 2019-12-13 16:18 I don't really understand this cavity filter. Is it always at that fulcrum? Why do we need to make a turn here...

“I don’t really understand this cavity filter.”

I don't understand the problem about this filter either. I suggest you ask Chunyang.

btty038

maychang posted on 2019-12-13 16:24 If the filter is placed between the stages, it will not be damaged due to the low power. However, since most power amplifiers work in Class C or Class B, it will definitely cause a strong...

Can the output be suppressed within the frequency band considered using the isolation of the combiner?

btty038

If each resonant point is constantly exposed to the power of the harmonics of the power amplifier, it will generate heat and fail to dissipate the heat, causing the solder of the device to melt and then damage the device.

btty038

Of course, what I posted on the 191st floor is a regular LC filter. During the debugging, I found that this phenomenon would occur when connecting the power amplifier and the filter part